Q: Why do I get a message when trying to sync my iphone to my computor saying ipone xxxxxx cannot be synced with this computor because it is not authorised. The store drop down list indicates the computor is already authorised.

Hi Bundoo,

Welcome to the Support Communities!  If you are repeatedly asked to authorize your PC using iTunes for Windows, try these troubleshooting steps:

iTunes repeatedly prompts to authorize computer to play iTunes Store purchases - Apple Support
http://support.apple.com/en-us/HT203160

Turn Off User Account Controls (Windows Vista and later)

Turning off User Account Controls then turning it back on often resolves issues with authorization. To do this:

1. Access the Control Panel.
   • Windows Vista and Windows 7: Choose Start > Control Panel.
   • Windows 8: Move the cursor to the top-right corner and click Settings and then Control Panel
2. Click "User Accounts and Family Safety."
3. In the User Accounts window, click User Accounts.
4. Windows Vista: Click "Turn User Account Controls on or off."
   Windows 7 and Windows 8: Click "Change User Account Control settings."
5. Windows Vista: Deselect the option to "Use User Account Controls (UAC) to help protect your computer."
   Windows 7 and Windows 8: Move the slider to the bottom setting "Never notify".
6. Click OK.
7. Restart your computer.
8. Access the Control Panel.
   • Windows Vista and Windows 7: Choose Start > Control Panel.
   • Windows 8: Move the cursor to the top-right corner and click Settings and then Control Panel.
9. Click "User Accounts and Family Safety."
10. In the User Accounts window, click User Accounts.
11. Windows Vista: Click "Turn User Account Controls on or off."
    Windows 7 and Windows 8: Click "Change User Account Control settings."
12. Windows Vista: Select the option to "Use User Account Controls (UAC) to help protect your computer."
    Windows 7 and Windows 8: Move the slider back to the desired setting.
13. Click the OK button.
14. Restart your computer.
15. Authorize your computer with your iTunes Store account.

 

Remove the SC Info folder

If you're still unable to authorize your computer to play your purchases, you may be able to resolve your issue by removing the "SC Info" folder. To do so, follow these steps:

Windows

1. Quit iTunes.
2. Access the file system on the computer.
   • Windows 8: Move the cursor to the upper-right and click the magnifying glass. In the search bar, type %ProgramData% and press the Return key.
   • Windows Vista and Windows 7: Click Start. In the search bar, type %ProgramData% then press the Return key.
   • Windows XP: Click Start and choose Run. Type %allusersprofile% and click OK.
3. Show hidden files.
   • Windows 8: Click View and then click Options. On the View tab, select "Show hidden files, folders, and drives."
   • Windows Vista and Windows 7: Click Organize and then "Folder and search options." On the View tab, select "Show hidden files, folders, and drives."
   • Windows XP: Click Tools and then choose Options. From the View tab, select "Show hidden files and folders."
4. Navigate to the SC Info folder.
   • Windows Vista and later: Open the Apple Computer folder and then the iTunes folder.
   • Windows XP: Open the Application Data folder, then the Apple Computer folder, and then the iTunes folder.
5. Right-click the SC Info folder and choose Delete.
6. Restart the computer.
7. Open iTunes.
8. Authorize your computer to play your purchases.
   • Note: If you have multiple accounts, you'll need to authorize your computer for each account.

I hope this information helps ....

- Judy